The statement that an orthodromic pathway will show a delta wave on the ECG is true.

The statement that an orthodromic pathway will show a delta wave on the ECG is true.

• A. True
• B. False
• C. It depends on conduction velocity
• D. Cannot be determined

Answer: (B)

Delta waves reflect pre-excitation of the ventricles through an accessory pathway. In orthodromic AVRT, the impulse travels anterogradely via the AV node and only uses the accessory pathway retrogradely for conduction back to the atria. Because the ventricles are activated through the normal His-Purkinje system, there is no pre-excitation and no delta wave on the ECG. If the antegrade conduction used the accessory pathway (antidromic AVRT), or in a WPW pattern with true pre-excitation, a delta wave would appear. So the statement is false because orthodromic conduction does not produce ventricular pre-excitation.

Delta waves reflect pre-excitation of the ventricles through an accessory pathway. In orthodromic AVRT, the impulse travels anterogradely via the AV node and only uses the accessory pathway retrogradely for conduction back to the atria. Because the ventricles are activated through the normal His-Purkinje system, there is no pre-excitation and no delta wave on the ECG. If the antegrade conduction used the accessory pathway (antidromic AVRT), or in a WPW pattern with true pre-excitation, a delta wave would appear. So the statement is false because orthodromic conduction does not produce ventricular pre-excitation.